Conventionally, there has been known a system which monitors body movement of a patient who is lying on a bed or a care-receiver (hereinafter collectively called a “watching target person”) with an imaging apparatus in a hospital, a care facility, etc. Further, there has been known an apparatus which extracts the bed area based on the captured image in monitoring the watching target person using such a system.
However, in the hospital or the care facility, a bed installation position is not always fixed. That is, the bed may be moved. Due to this, it is not possible to uniquely determine the positional relationship between the bed and the imaging apparatus. Accordingly, it is desired to extract the bed area based on the captured image regardless of the positional relationship between the bed and the imaging apparatus.
In order to realize the extraction, for example, there are (a) a known method of extracting the bed area by using pattern matching based on a bed shape, and (b) another known method of extracting the bed area based by classifying the line segments of the image area into an upper end, a lower end, a left side, and a right side and averaging the respective line segments.
References are made to Japanese Laid-open Patent Publication Nos. 2011-103037 and 2005-327244.
Reference is made to Panachit Kittipanya-Ngam, Ong Soh Guat, Eng How Lung, “Bed Detection For Monitoring System In Hospital Wards”, 34th Annual International Conference of the IEEE EMBS, San Diego, Calif. USA, 28 Aug.-1 Sep. 2012, p. 5887-5890.